Electrical process tomography: seeing "without eyes" inside stirred vessels

Body-scanning exploiting 3-D imaging has revolutionised diagnostics and treatment in medicine. Process engineers would like to be similarly able to image chemical process units in 3-D, but without the ￡multi-million price tag. UMIST and Leeds University have together, through the Virtual Centre for Industrial Process Tomography (http://www. vcipt.org), pioneered several electrical process tomography techniques and used them in a variety of applications. Illustrations are presented to show how electrical resistance tomography (ERT) has been developed for typical stirred vessels widely encountered in batch process manufacturing. The technique is potentially fast and inexpensive and capable of imaging both dynamic and pseudo-stationary processes. Examples from UMIST's two-tonne vessel will be presented for miscible tracer mixing, as well as gas-liquid and solid-liquid mixing.     

THE EFFECT OF SERIAL RETESTING ON THE RELATIVE PERFORMANCE OF HIGH- AND LOW-TEST ANXIOUS SEVENTH GRADE STUDENTS1

Serial retesting was investigated as a means of improving the test performance of high-anxious students relative to that of their low-anxious peers. The Test Anxiety Scale for Children was given to about 300 seventh grade students in a suburban school; the middle 50% were eliminated to maximize experimental variance. Six groups were established for high and low anxiety levels and for three ability levels. The Academic Promise Tests (except for the Abstract Reasoning Test) were then given four times at 1-week intervals in the fall of the school year. All groups continued to improve significantly in a monotonic, linear fashion, with the greatest improvement occurring on the Numerical Test. Contrary to expectation, there were no significant interactions among previous achievement levels, predispositional test anxiety levels, and test trials. The greatest change on the Numerical Test occurred between the first test trial and the second test trial.     

Electrical process tomography： seeing “without eyes” inside stirred vessels

INTRODUCTION Stirred vessels are widely used in the chemical industry as fluid mixing devices. These vessels at manufacturing scale often have more than a passing resemblance to the beaker used in the chemical laboratory to gather information on chemical path- ways and reaction kinetics. Such oversimplified scale-up, based on simple geometric similarity at the small and large scales, is supposed to greatly reduce the uncertainty in scaling-up for manufacture. This “empirical” approach i…